96 lines
2.7 KiB
Haskell
96 lines
2.7 KiB
Haskell
module Compiler where
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import Constant
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import Control.Monad
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import Data.Char (isUpper)
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import qualified Data.Map as M
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import Code (Code, Datum(..), Heap, Id(..), Instr(..))
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import Heap (heapStruct)
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import IR (PrlgInt(..), StrTable(..))
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varname :: String -> Bool
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varname ('_':_) = True
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varname (c:_) = isUpper c
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varname _ = False
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varOccurs :: PrlgInt -> M.Map Int Int
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varOccurs (CallI _ xs) = M.unionsWith (+) $ map varOccurs xs
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varOccurs (VarI idx) = M.singleton idx 1
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varOccurs _ = M.empty
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variablizePrlg :: Int -> StrTable -> PrlgInt -> PrlgInt
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variablizePrlg void (StrTable _ _ itos) = go
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where
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go (CallI i ps) = CallI i $ map go ps
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go o@(ConstI (Atom i))
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| i == void = VoidI
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| varname (itos M.! i) = VarI i
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| otherwise = o
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go x = x
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renumVars :: (Int -> Maybe PrlgInt) -> PrlgInt -> PrlgInt
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renumVars rename = go
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where
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go (CallI i ps) = CallI i $ map go ps
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go (VarI idx)
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| Just new <- rename idx = new
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go x = x
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squashVars :: PrlgInt -> PrlgInt
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squashVars x =
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let occurs = M.assocs (varOccurs x)
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m' =
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M.fromList $
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[(idx, VoidI) | (idx, n) <- occurs, n <= 1] ++
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[(idx, VarI idx') | ((idx, n), idx') <- zip occurs [1 ..], n > 1]
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in renumVars (m' M.!?) x
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squashChoices :: [Code] -> Either String Code
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squashChoices = out . concatMap go
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where
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go [Choices cs] = cs
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go x = [x]
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out [] = Left "goal compilation has no choices?"
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out [x] = pure x
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out xs = pure [Choices xs]
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compileGoals :: Int -> Int -> Int -> PrlgInt -> Either String Code
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compileGoals andop orop cut = fmap (++ [Done]) . go'
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where
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go' = struct2goal >=> go
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go p@(CallI x args@[_, _])
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| x == andop = concat <$> traverse go' args
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| x == orop = traverse go' args >>= squashChoices
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go p@(CallI x [])
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| x == cut = pure [Cut]
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go x = compileGoal x
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compileGoal :: PrlgInt -> Either String Code
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compileGoal = fmap compileArg . struct2goal
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compileArg :: PrlgInt -> Code
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compileArg (CallI i args) =
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U (Struct Id {str = i, arity = length args}) : concatMap compileArg args
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compileArg (ConstI c) = [U (C c)]
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compileArg (VarI x) = [U (LocalRef x)]
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compileArg (VoidI) = [U VoidRef]
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seqGoals :: [Code] -> Code
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seqGoals = (++ [Done]) . concat
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heapStructPrlgInt :: Monad m => m PrlgInt -> Heap -> Int -> m PrlgInt
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heapStructPrlgInt heaperr heap ref = heapStruct atom struct hrec heap ref
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where
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atom (C c) = pure (ConstI c)
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atom VoidRef = pure $ VoidI
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struct (Struct s) args = pure $ CallI (str s) args
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hrec (HeapRef r) ref
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| r == ref = pure $ VarI r
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| otherwise = heaperr
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struct2goal :: PrlgInt -> Either String PrlgInt
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struct2goal (ConstI (Atom s)) = pure $ CallI s []
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struct2goal call@(CallI _ _) = pure call
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struct2goal x = Left $ "cannot compile goal: " ++ show x
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